OVER-EXPRESSION OF OXYTOCIN IN THE TESTES OF A TRANSGENIC MOUSE MODEL

The bovine oxytocin gene has been expressed in the testes of two indep endent transgenic mouse lines. Hybridization and RNase protection anal ysis showed that the oxytocin transgene was transcribed from the norma l functional promoter in the Sertoli cells of the seminiferous tubules in a developmentally regulated manner. Immunohistochemistry indicated that both oxytocin and neurophysin epitopes were expressed together i n the Sertoli cells at stages I-V and X-XII of the cycle of the semini ferous epithelium. Furthermore, analysis with high- performance liquid chromatography showed that there was a tenfold increase in the amount of amidated oxytocin present in testicular extracts from the transgen ic mice. However, there appeared to be no detectable effect of this ov erproduction of hormone on testicular morphology or fertility paramete rs. A significant decrease by 50% was detected only in the levels of i ntratesticular testosterone and dihydrotestosterone. The results point to a local paracrine role for oxytocin in the modulation of Leydig ce ll function.